A panel of experts says that 6.2 million people in the U.S. have diabetes without realizing it.

That's about 30 percent of the cases, they said in a report.

That means the nation needs to improve how it screens for and diagnoses the condition, said lead author Dr. Christopher Saudek of the Johns Hopkins School of Medicine.

Saudek said one problem is that the most common test requires fasting. Since most people eat before going to the doctor, they can't be diagnosed until the disease has gotten more serious.

The panel suggested other tests, such as those that measure hemoglobin in the blood, which can also indicate glucose levels. That test does not require fasting.

A news release on the report said that the current recommendations for how to test for diabetes were made 10 years ago.